A slot is a term used in computer hardware to refer to an expansion slot, such as an ISA (Industry Standard Architecture), PCI or AGP (accelerated graphics port) slot. It may also refer to a memory slot on a motherboard.

Almost a century after they first ushered in the golden age of gambling, slot machines remain a powerful force in the United States, generating millions of dollars a day in profits and triggering a wave of addiction-related problems that has led to the closure of saloons, dance halls and now casinos. Mental health experts say the games are psychologically deceptive and can make gambling addicts out of people who aren’t predisposed to addictions. Advocates for the industry argue that the machines are benign and designed to entertain, not manipulate.

The simplest mechanical slot machine is a reel with several stop positions and a payline, with symbols displayed on the screen. A player inserts cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode, then activates the machine by pulling a lever or pushing a button. The reels spin and then stop to rearrange the symbols in a winning combination, paying credits according to a paytable. Most slot machines have a theme, with classic symbols including fruit and stylized lucky sevens.

On a recent visit to Bally, the Las Vegas-based manufacturer of slot machines, hundreds of the latest cabinets lined a warehouse, sporting the industry’s signature black exterior and jutting dashboards. The numbered tags attached to each indicated their destination, most going to Oklahoma, Washington and Michigan, with a few bound for casinos in Vegas.